for those using oceanic salt

[zapata41]

i was just wondering if someone out there with a refractometer could tell me how much salt( like 1/2 cup or 3/4) per gallon of water to attain 1.025 sg , i currently add a little until the ol' swing arm gets to about 1.025 not the best methoud i know

Thanks
Tim

[Daemonfly]

Well, until someone else posts with more detailed info, I usually average around 1.025-1.026 with 1/2 cup per gallon. It does vary here & there, and my new batch of salt seems a bit more "potent" than the smaller bag I had before.

[comatose]

the best thing to do is measure it the first time you use it and count the cups till you get it exactly at 1.025 in your mixing container, then write it down and always use that amount. but always check anyway.

reason being all salt mixes aren't the same. but i use Oceanic and i start off with 1/2 cup per gallon.

if you change salts you will have to remeasure again.

[grim]

While the swing arm isn't the best method, neither is using a 'recipe' to mix up your water. I'd suggest you find someone locally to help you 'calibrate' your swing arm with their refractometer.

You'll need a thermometer, your swing arm, their refractometer, and a sharpie marker.

Mix up water to target salinity and temperature using the thermometer and their refractometer. Now, test with your swing arm, make sure there are no bubbles on the arm, and make a mark with the sharpie, there is your target.

When you mix up saltwater in the future, make sure you are mixing up to the same temperature. While swing arms may be 'off' their scales (read high or low), I've found them to generally be pretty consistent with their reading if the temperature is stable. While number of cups is a good double check to make sure everything is right, I'd trust a swing arm (especially if confirmed) over counting cups.

Always rinse your refractometer in RO (/DI) well after you use it, and *always* check for bubbles.

jb

[Randy Holmes-Farley]

You can also calibrate your swing arm using table salt, as I describe in this article:

Reef Aquarium Salinity: Homemade Calibration Standards
http://reefkeeping.com/issues/2004-06/rhf/index.htm

[thrlride]

I know someone that has a FO, his wife claims that he knows exactly how much salt to put in to get the desired salinity. I would love to take my refractometer there and see where it is at. Just once. :)

[zapata41]

well thanks soo much for the help, will have to find a refracto somewhere local and calibrate

Tim

[Randy Holmes-Farley]

You're welcome.

Good luck! :)